Ulrich, Didier Talking about forces, gravitational fields etc makes no physical sense if the observer's reference frame isn't specified. For an observer in/on a satellite orbiting about the Earth with their reference frame fixed with respect to the satellite. There is no gravitational field, whatever methods chosen to measure a gravitational field (within the satellite) will always produce a null result. Pendulum clocks fail to work, given an initial push they will just rotate around the pivot, provided the pivot suitably constrains the motion of the pendulum (ie a shaft running in a set of ball or roller bearings or similar and not a knife edge pivot).
If, however the satellite acts as a rigid body and has a large enough diameter then it would be possible for an observer on the satellite to detect a gravitational field gradient. If the satellite is large enough and orbits close enough to the Earth, this gravitational field gradient would tear the satellite apart. For an observer located on the Earth however the motion of the satellite can be accurately described by Newtonian mechanics where the centripetal pull of gravity acts on the satellite causing it to have a centripetal (radial) acceleration as it orbits the Earth. Bruce _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts